通过块对角步进预处理实现的光谱计算机断层成像的三种材料分解
Three material decomposition for spectral computed tomography enabled by block-diagonal step-preconditioning
摘要：
具有多能量窗光子计数探测器的光谱计算机断层成像（CT）的潜在应用是具有K边缘造影剂的定量医学成像。利用这种造影剂的谱CT的图像重建需要以至少三个扩展函数（例如，骨/水/K边缘材料或光电过程/康普顿过程/K边缘材料）来表达X射线线性衰减图。使用三个展开函数可能导致应用于光谱CT的迭代图像重建（IIR）算法收敛缓慢。我们提出了一个块对角步进预处理器，用于与原始-对偶迭代图像重建框架，我们一直在开发的光谱CT。我们证明了新的阶跃预处理器在灵敏光谱CT模拟上的优势，其中测试对象具有低浓度的钆（Gd）造影剂，X射线衰减图由三种材料表示- PMMA，软组织等效物，铝，骨等效物和Gd。
英文摘要：
A potential application for spectral computed tomography (CT) with multi-energy-window photon-counting detectors is quantitative medical imaging with K-edge contrast agents. Image reconstruction for spectral CT with such contrast agents necessitates expression of the X-ray linear attenuation map in at least three expansion functions, for example, bone/water/K-edge-material or photo-electric- process/Compton-process/K-edge-material. The use of three expansion functions can result in slow convergence for iterative image reconstruction (IIR) algorithms applied to spectral CT. We propose a block-diagonal step-preconditioner for use with a primal-dual iterative image reconstruction framework that we have been developing for spectral CT. We demonstrate the advantage of the new step-preconditioner on a sensitive spectral CT simulation where the test object has low concentration of Gadolinium (Gd) contrast agent and the X-ray attenuation map is represented by three materials - PMMA, a soft-tissue equivalent, Aluminum, a bone equivalent, and Gd.
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